Telephone system



Feb. 7, 1933. w. KAPP v 1,896,315

TELEPHONE SYSTEM Filed March 25, 1932 a; Hm L DIFFERENT/AL g 8 1 fi N 8 u q Inu'eniur William F. KE FP Patented Feb. 7, 1933 UNITED STATES PATENT mm WILLIAM EKAPP, or ELMHURST, ILLINOIS, ASSIGNOR To ASSOCIATED ELECTRIC Lane- RATORIES, Inc, or CHICAGO, ILLINOIS, A CORPORATION or E AWARE TELEPHONE SYSTEM,

Application filed March 25, 1932. Serial so. 601,146.

- conversation at a time.

Another object of the invention is to provide a new and improved arrangement for generating the ringing current in small telephone systems. In small telephone systems wherein the installation of a ringing current generator of the usual type is unwarranted,

arrangements have been provlded heretofore for generating ringing current by the operation of the calling subscriber s dlal. In these systems, however, the ringing current pro-- duced is of a very low frequency, corresponding to the frequency of the dial impulses, which are ordinarily transmitted at the rate of ten impulses a second. In the present sys tem, ringing current generation is controlled inthe same manner pointed out above; that is, by means of the calling subscribers dial. However, arrangements have been provided for increasing the frequency of the generated ringing current so that it is much higher than has been possible heretofore with this type of ringing. This results in a very satisfactory ringing signal for the wanted subscriber, and is a decided improvement over the prior systems.

Ihe above pointed out objects, together with others not specifically mentioned at this time, will appear more fully in the specification which is to follow.

Referring now to the drawing, there is illustrated therein, by means of the usual circuit diagrams, sufiicient of the apparatus in a system embodying the principles of the invention to enable the invention to be thoroughly understood.

The automatic substation A, B, and C, shown therein, which are substations of the same common-talking private automatic exchange, are ordinary automatic substations having the usual talking and signalling instrumentalities and having in addition the calling devices, CD, CDl,=and D2, respec tively, for the purpose of controlling the switching mechanism SM. The rotary switch SM is of the well-known, single-leveh'step' by-step type. ,Its wipers38 andr39 are ad vanced step by step under control of combi: nation battery-feed and line relay 23to select a conductorextending to the ringer of the wanted-subscribers substation. The transformer T and differential relay 27 are provided for the purpose of generating the ringing current for signalling thelwanted subscriber.

A brief description of the apparatus having been given, the operation will be ex plained more in detail. For this purpose, it

will be assumed that the subscriber atsubstation A desires to call the subscriber at substation C, whose substation is connected to the same common-talking line, In order to do this, the subscriber at substation A removes his receiver and then dials the number of the subscriber at substation C.

When the receiver is removed at substation A, line relay 23 energizes over line conductors 21 and 22. Upon energizing, line relay 23 completes a circuitfor the slowacting release relay 24. At armature 30, release relay 24 opens a point in the restoring circuit and prepares a circuit for the slowacting series relay 25 and the rotary magnet V The calling subscriber at substation A may now proceed to operate his calling device CD in accordance with the digit 3, compr sing the desired subscribers number. As a result, three interruptions are produced in the circuit of the line relay 23. In response to the first deenergization of line relay 23, an impulse ofcurrent is transmitted atarmature 29 to the slow-acting series relay 25 and rotary magnet 28 through the operated armature 80 and wiper 38 of the rotary switch SM in its normal or home position; The slowact-ing series relay 25 and the rotary magnet 28 energizes in series over thiscircuit. Series relay 25, upon energizing, prepares a new cir-' cuit path for itself and therotary magnet 28 16c The series relay 25, being slow releasing, re-

mains in .itsoperated position, but the rotary magnet28 falls back, thereby advancing its wipers 38 and 39 into engagement with the first set of bank contacts.

In response to each succeeding momentary interrupt1on constituting the d1g1t3, line relay 23 again restores and completes a circuit for series relay 25 and the rotary magnet 28 atarmature 29 and its resting contact. Since wiper 38 has been advanced from its home position, the circuit for series relay 25 and rotary magnet 28 now includes the operated armature 31. The series relay 25 accordingly remains operated, and the rotary magnet 28 responds by advancing the wipers 38 and 39 two more steps into engagement with the third set of bank contacts.

At the termination of the impulse series, line relay 23 remains in its energized position and maintains release relay 2i energized. However, the slow-to-release series relay 25 soon falls back and transfers the impulsing circuit to the slow-to release, ringing-control relay 26. I

The switching mechanism SM is now in a position to respond to impulses, constituting the digit 0, for example, transmitted by the calling subscriber at substation A, to transmit ringing current over wiper 39 and conductor 43 to operate the ringer at the called substation C. The signalling of the called subscriber is accomplished in the following manner:

When the calling subscriber dials the ringing digit 0, line relay 23 is momentarily restored ten times. Each time line' relay 23 falls back, it completes the impulse circuit which has been extended by way of armature 31 to relay 26. Relay 26, therefore, operates and remains operated throughout the series of impuses. At armatures 32 and 33, relay 26 connects the windin gs of differential relay 27 to the front and back contacts,'respectively, of armature 29. I

Y \Vhen relay 26 connects up the windings of relay 27, relay 23 being in a restored condition, relay 27-, is at once operated through its upper, winding. The closing of the front contact of armature 34 of relay 26 results in the closure of a circuit for the right hand primary winding of transformer T, by way of resistance and armature 34 of relay 26.

When line relay 23 again energizes at the termination of the momentary interruption er winding of the relay.- Responsive to the opening of the circuit of its upper winding, relay 27 starts to become demagnetized. Moreover, the relay starts to become magnetized in the opposite direction responsive to current flow in its lower winding. Therefore, armature 35 will restore and engage its resting contact while the magnetism is passing through the zero point (while reversing in direction), thereby completing a circuit for the left-hand primary winding of transformer Thy way of resistance 40.

The magnetism generated by the lower winding of relay 27 eventually becomes strong enough to reoperate armature 35, whereupon the circuit is transferred from the left-hand winding of the transformer T, to the right-hand winding. Since each winding of relay 27 opposes the other, it is evident that relay 27 is caused to restore and reoperate each time armature 29 of relay 23 is released or attracted.

This operation continues until the line relay has been momentarily deenergized ten times responsive to the dialling of the digit 0, with the result that the differential relay 27 has been momentarily energized twenty times. Relay 26 new releases and disconnects the windings of relay 27 at armatures 32 and 33, while at armature 34 it opens the primary'circuit'at transformer T.

The first time armature 35 and its front contact is closed, the current flow through the right-hand, primary winding of't'ransformer T causes an induced current to be generated in one direction in the secondary winding of the transformer. Responsive to the opening of this circuit and to the closely following closure of the circuit through the left-hand, primary winding, an induced current is generated in the other direction in the secondary winding of transformer T. Each time line relay 27 changes position, the magnetism in the transformer is reversed and a half cycle of current is generated in the seeondary winding. Since relay 27 operates ten times and restores ten times, twenty cycles of alternating current are generated in the secondary winding of the transformer.

Responsive to the alternating current generated by the opening and closing of the circuit through the rightand left-hand, primary windings of transformer T, the bell at substation C vibrates. The circuit in which theinduced alternating current flows is as follows ground, secondary winding of transformer T, wiper 39 and its engaged third bank contact, conductor e3, condenser and ringer at substation C, switchhcok, lower line conductor 22, and the lower winding of line relay'23, to ground. I

If the subscriber at substation C does not answer the call, the subscriber at substation A may resignal him by again diallin the respond inthe manner described above to cause the transmission "of induced alternating current by way of the secondary winding of transformer T to again ring the bell at the substation C. 1

llThen the subscriber at substation Cremoves his receiver to answer the call, the ringer is disconnected and his transmitter and receiver are bridge-d across-the line conductors 21 and 22, so thatthe conversation between the subscriber at substationA and substation C may now take place Should either subscriber inadvertently operate his calling device at the present time, it will have no effect on the switch SM, since the line relay will not follow the dial at one station with the receiver removed at another station.

Talking current for the calling and called.

subscriber is supplied fromthe windings'of line relay 23. The talking path is indicated by the heavy conductors.

When the conversation. is finished, both subscribers replace their receivers. When the last party has replaced his receiver, the circuit for line relay 23 is opened. Upon deenergizing, line relay 28 breaks the circuit for release relay 24, which subsequently deenergizes and completes a circuit for operating the rotary magnet 28 to restore its wipers to their normal or home position. The circuit for restoring the wipers to normal or home position is asfollows: ground, armature 29 and its resting contact, armature 30 and its resting contact, ofi-normal contact 3? (closed on the first step of the wipers of the switch), self-interrupting contact 36, winding of the rotary magnet 28, to battery. Ros tary magnet 28'energizes over this circuit, and upon energizing opens its initialen-ergizing circuit at its selfdnterrupting contacts 36. This opens the circuit for the rotary magnet and causes it to deenergize and advance its wipers to the next bank contact. hen the self-interrupting contacts restore, the circuitis again completed for energizing the magnet, which accordingly responds and opens its energizing circuit again at its selfinterrupting contacts 86 and advancesv the wipers another step. The advancement of V the wipers continues untll the wipers of the switch are advanced to their home position, at which position the off-normal contacts 37 are opened and the switch is accordingly brought to rest.

When the subscriber at substation C desires to establish a connection with the subscriber at substation B, for example, he-will remove his receiver and dial the digit 2, which i will cause the wipers of the switch SM tobe advanced to their associated second bank contacts to engage conductor 42. The subscriber will now dial the digit 0, or any other desired ringing digit, which will cause the ringer at substation B to respond in the manner previreplaced their receivers takes placeas previously described.

What is claimed is: l

1. In atelephone system, a commonltalk ing line provided with a plurality of subscribers stations, a plurality of individual signalling" conductors, aswitch, means controlled from one of said stations for operating said" switch to'connect with any one of said conductors, and means controlled by the operation ofthe calling subscribers dial after said connectionhas beenestablished for transmitting signalling current over the con-- nected conductor'to signal the wanted subscriber on saidlinel' '2. In a telephone system, the combination with. a common talking line provided with a plurality'of subscribers stations, of an automatic switch, a plurality of individualsig'e nalling conductors extending to said. stations, respectively," -means controlled over said line for connecting said switch to any one of said signalling conductors, and means controlled over said line after said signalling conductor has been connected for generating ers station'to select the wanted subscriberzs signalling conductor, and signalling means operated under control of the .calling" subscribers dial for generating signalling'current to operate the signal at the wanted subscribers station over the selected conductor.

4. In an automatic telephone system, an automatic switch, a signallingconduetor, means for operating said switch to connect up to said] conductor, and directively-controlled means in said switchfor generating signalling current, said generating means compris ing a difi'erential relay'and a transformer.

5. In atelephone system, a line terminating at a common switching point, a plurality of subscribers stations on said line, individual signalling conductors extending from said common switching point to said stations, re s'pectively, ringing-current generatingmeans directively controlled by a callin subscriber, and a signalling circuit for each of said stations including the secondary winding of said transformer and the individual signalling conductor of the station in series. a i

6. In combination with a plurality of tele means responsive to the impulses of a first digit for operating the connector over sald common talking conductors to select a desired ringing conductor, and means responsive to the impulses of a second digit for generating alternating current and for transmitting the current over said ringing conductor to signal a wanted subscriber.

7. In an automatic telephone system, a common talking line terminating in an automatic switch, aline relay in said switch operated under control of the calling subscriber, individual conductors from each of said stations, respectively, terminating in said switch, means responsive to the operation of said line relay for advancing said automatic switch to select one of said signalling conductors, a differential relay, and means responsive after the termination of said selecting. operation for controlling said differential relay to transmit alternating current over the selected signalling conductor to operate the ringer at the Wanted subscribers station, said differential relay being operated under control of said line relay and responding twice as many times as the line relay responds to the impulses dialled by the calling subscriber. r

8. In a telephone system, an automatic switch, a plurality of subscribers connected to a common-talking line, an individual signalling conductor for each of said subscribers, means at said stations for transmitting impulses over said line to operate said switch to select one of said conductors and for then transmitting impulses for generating alternating current to signal the subscriber individual to said conductor, and means for causing said current to have a frequency'double the frequency of the impulses transmitted to generate it.

9. A switching device, means for transmitting series of impulses of a particular fre quency to said device, means in the device responsive to one series of impulses for setting the device, and means in the device responsive to a subsequent series of impulses for generating an alternating current of a frequency greater thanthe frequency of the received impulses. V

10. A switching device, means for transmitting series of impulses of aparticular frequency to said device, means in the device responsive to one series of impulses for setting the device, and means in the device responsive to a subsequent series of impulses for generating an alternating current whose frequency is double the frequency of the impulses of the subsequent series.

11. A switching device, means for trans mitting series of impulses of a particular frequency to said device, means in the device responsive to one series of impulses for setting the device, and means in the device responsive to a subsequent series of impulses for generating an alternating current of a frequency which is a multiple of the frequency of the impulses of the subsequent series.

12. In an automatic switch, a line relay controlled by impulses from a calling subscriber, a magnet operated responsive to said impulses to set said switch, and means controlled by said line relay responsive to subsequent impulses for generating a signalling ing twice the frequency of the impulses transmitted to generate the same.

14. In a telephone system, a common talking line provided with a plurality of subscribers stations, a plurality of individual signalling conductors, an automatic switch, means controlled from one of said stations for operating said switch to connect to any one of said conductors, and means in said switch directively operated from said station for generating twenty-cycle ringing cur rent to signal the wanted subscriber over the selected conductor.

15. In an automatic telephone'system, a common talking line having a plurality of subscribers stations thereon, an automatic switch, individual signalling conductors, means at'said stations for controlling said switch to select one of said conductors, and means responsive to a subsequent operation of said controlling means for generating alternating current to operate a signal at the wanted subscribers station over the selected conductor.

16. In a telephone system, a common talk- 1ng line provided with a plurality of subscribers stations, a plurality of individual signalling conductors, an automatic switch controlled over said line by a calling subscriber to select one of said conductors, a transformer, means for opening and closing a circuit including the primary winding of I said transformer, said means operated under control of said calling subscriber, and a signal connected to the selected signalling conductor operated responsive to the induced current generated in the secondary winding of the transformer by the opening and closmg of the circuit including the primary winding to signal the subscriber at the wanted station.

17. In a telephone system, a plurality of subscribers stations having common talking and individual ringing conductors, an automatic switch controlled over the common talking conductors by a calling subscriber to select the ringing conductor of the wanted subscriber, a transformer having its primary winding divided into tvvo'sections, a circuit for each of said sections, a relay controlled by said calling subscriber after the selection of said ringing conductor for rapidly opening and closing said circuits, and a signal at the wanted subscribers station connected to said conductor operated responsive to the current induced in the secondarywinding of said transformer by the opening and closing of said circuits.

18. In an automatic switch, a magnet, means responsive to a first series of impulses transmitted by a calling subscriber for operating said magnet to select a Wanted subscriber, and means responsive to a second series of impulses forgenerating alternating current for signalling the selected subscriber.

'19. In a signalling system, an impulse receiving device, an alternating current generator, and means controlled by said device for causing said generator to generate alternating current of a frequency greater than the 2 frequency of the received impulses.

20. In a signalling system, an impulse receiving device, a transformer arranged to deliver current impulses of a frequency double the frequency of the received impulses, control means interposed between said device and said transformer, means for causing said control means to be operated twice each time an impulse is received by said device, and means including circuit connections controlled by said control means for causing said transformer to deliver said current impulses.

In Witness whereof, I hereunto subscribe my name this 18th dayof March, 1932.

WILLIAM F. KAPP. 

